In Heinlein’s story, genetic technology is used by couples to control which of the children they could produce they do produce. With the assistance of expert advice, they select among the eggs produced by the wife and the sperm produced by the husband the particular combination of egg and sperm that will produce the child they most want to have, the one that does not carry the husband’s gene for a bad heart or the wife’s for poor circulation, but does carry the husband’s good coordination and the wife’s musical ability. Each couple gets its own child, yet characteristics that parents do not want their children to have are gradually eliminated from the gene pool. Since the decision is made by each set of parents for their own children, not by someone for everyone, it should maintain a high degree of genetic diversity; different parents will want different things. And since parents, unlike state planners, can usually be trusted to care a great deal about the welfare of their children, the technology should mostly be used to benefit the next generation, not to exploit it. (p. 190)

The technical term for this is germ-line genetic engineering. Surprisingly enough, it is not the only way of altering living things by changing their genes. The alternative is to alter genes in the cells of an already existing organism. This raises an obvious problem. Altering the genes in a single cell is a difficult and chancy procedure. A single human body contains about 100 trillion cells. How can one possibly alter enough of them to make a difference?

This problem was solved a very long time ago, and not by humans. Viruses reproduce by hijacking the mechanism of a cell, modifying it, and using it to produce more viruses. Since viruses hijack us, it seems only fair for us to hijack them.

"A retrovirus contains a message written in RNA which reads, in essence: ‘Make a copy of me and stitch it into your chromosome.’ All a gene therapist need do is take a retrovirus, cut out a few of its genes …, put in a human gene, and infect the patient with it. The virus goes to work inserting the gene into the cells of the body and, lo, you have a genetically modified person." (Ridley, Genome, p. 247)

This form of genetic engineering has already been used to combat severe combined immune deficiency – SCID – the genetic disease that makes children’s bodies unable to defend themselves against infection.(...) Similar cures are being developed for a variety of other diseases. (pp. 193-194)

Implicaciones para la rehabilitación de criminales:

The possibility of retrofitting cells with new genes also suggests a tempting, and disturbing, possibility for high-tech law enforcement. Suppose we conclude that some of the causes of criminal behavior are genetic; perhaps that there is a gene, more likely a group of genes, for psychopathy. Instead of sentencing a criminal to be imprisoned we sentence him to have his genes revised – a brand-new, high-tech version of the old dream of reforming criminals instead of deterring them.

When we are finished altering some of the genes in every cell in his body – I am assuming a more advanced version of the technology than we have at present – is he still the same person? Have we reformed or replaced him? (pp. 194-195)

¿Dictaduras manipulando genes para crear súbditos a medida?:

A dictatorial government might try to engineer the entire population, to breed some inconvenient characteristic, say aggressiveness or resistance to authority, out of it. A less ambitious government might use cloning to produce multiple copies of the perfect soldier, or secret policeman, or scientific researcher, or dictator – although multiple identical dictators might be asking for trouble.

Such scenarios are more plausible as movie plots than as policies. It takes about twenty years to produce an adult human; few real-world governments can afford to plan that far ahead. And while a clone will be genetically identical to the donor, its environment will not be identical, so while cloning produces a more predictable result than sexual reproduction, it is far from perfectly predictable. Getting your soldiers, secret police, scientists, or dictators the old-fashioned way has the advantage of letting you select them from a large population of people already adult and observable.

One further argument against the idea is that if it is an attractive strategy for a dictatorial state, it ought already to have happened. Selective breeding of animals is a very old technology. Yet I know of no past society that made any serious large-scale attempt at selective breeding of humans in order to produce in the ruled traits desired by the rulers. (pp. 196-197)

Clonar humanos para salvar vidas:

In 1988, Anissa Ayala, then a high school sophomore, was diagnosed with a slow progressing but ultimately fatal form of leukemia. Her only hope was a treatment that would kill off all her existing blood stem cells and replace them by a transplant from a compatible donor. The odds that a random donor would be compatible were about 1 in 20,000.

Her parents spent two years in an unsuccessful search for a compatible donor, then decided to try to produce one. The odds were not good. A second child would have only a 25% chance of compatibility. Even with a compatible donor the procedure had a survival probability of only 70%. The mother was already forty-two, the father had been vasectomized. The alternative was worse; Anissa’s parents took the gamble. The vasectomy was successfully reversed. Their second daughter Marissa was born – and compatible. Fourteen months later she donated the bone marrow that – as she put it five years later in a television interview – saved her sister’s life.

Marissa was produced by conventional methods; the controversial element, loudly condemned by a variety of bioethicists, was producing a child in the hope that she could donate the bone marrow required to save another. But cloning, had it been practical, would have raised the odds of a match from 25% to 100%. (p. 197)

Genericos y genepobres:

What about technologies allowing parents to choose among the children they might have, or even to add useful genes, perhaps artificial, that neither parent carries? Lee Silver, a mouse geneticist and the author of a fascinating book on reproductive technology, worries that the long-term result might be a society divided into two classes: generich, the genetically superior descendants of people who could afford to use new technologies to produce superior offspring, and genepoor.

There are two reasons this is not likely to happen. The first is that human generations are long and technological change is fast. We might have a decade or two in which higher-income people have substantially better opportunities to select their children. After that the new technology, like many old technologies, will probably become inexpensive enough to be available to almost anyone who really wants it. It was not that long ago, after all, that television was a new technology restricted to well-off people. Currently, about 97% of American families below the poverty line own at least one color television.

The second reason is that human mating is not strictly intraclass. Rich men sometimes marry poor women and vice versa. Even without marriage, if rich men are believed to carry superior genes – as, after a generation or two of Lee Silver’s hypothetical future, they would be – that is one more reason for less rich women to conceive by them, a pattern that, however offensive to egalitarian sensibilities, is historically common. Put in economic terms, sperm is a free good, hence provides a low-cost way of obtaining high-quality genes for one’s offspring. I doubt we will get that far, but if we do we can rely on the traditional human mating pattern – monogamy tempered by adultery – to blur any sharp genetic lines between social or economic classes. (p. 199-200)

Retrasar la pubertad, ¿potestad de los padres o abuso del menor?

Suppose a drug company announces a new medication – one that will safely delay puberty for a year, or two years, or three years. I predict that there will be a considerable demand for the product. Are parents who artificially delay the physical development of their daughters guilty of child abuse? May schools pressure parents to give the medication to boys about to reach puberty, as many now do for other forms of medication designed to make children behave more as schoolteachers wish them to? If schools do require it, are parents who refuse to artificially delay the development of their sons guilty of child abuse – or at least subject to the same pressures as parents who today refuse to put their sons on Ritalin?

While we are at it, what about the application of a similar technology to other species? Cats are lovely creatures, but kittens are much more fun. If only they stayed kittens a little longer...

In Heinlein’s story, genetic technology is used by couples to control which of the children they could produce they do produce. With the assistance of expert advice, they select among the eggs produced by the wife and the sperm produced by the husband the particular combination of egg and sperm that will produce the child they most want to have, the one that does not carry the husband’s gene for a bad heart or the wife’s for poor circulation, but does carry the husband’s good coordination and the wife’s musical ability. Each couple gets its own child, yet characteristics that parents do not want their children to have are gradually eliminated from the gene pool. Since the decision is made by each set of parents for their own children, not by someone for everyone, it should maintain a high degree of genetic diversity; different parents will want different things. And since parents, unlike state planners, can usually be trusted to care a great deal about the welfare of their children, the technology should mostly be used to benefit the next generation, not to exploit it. (p. 190)